I wrote a small e-book about terrible tips for C++ developers. Actually, it describes bad programming practices and explains why it's better to avoid them. However, every chapter of this mini-book starts with a terrible tip — just for fun.

By the way, these tips may seem artificial but believe me, they are based on the real experience. In other words, the described terrible tips occur in developers' lives — that's why it's worth discussing them. First of all, this book will be useful for junior developers. But more skilled C++ developers can also find interesting and useful tips.

Even though it's a mini-book, it clearly does not fit into the Habr format. Too many words. So, I decided to write here the review. Here is the link to find the full version of the mini-book: 60 terrible tips for a C++ developer.

If you still hesitate whether to read it or not, below you will find a list of terrible tips that will be discussed in the mini-book.

View the terrible tips:

I'm Alex Movergan, DevOps team lead at Altenar. I focus on automation in general and on improving troubleshooting skills within my team. In this article, I'll share a captivating tale that revolves around Kubernetes, validation webhooks, kubespray, and Calico.

Join me on this DevOps journey as we explore real-world scenarios unraveling the intricacies of troubleshooting in a Kubernetes environment.

This is a series of articles dedicated to the optimal choice between different systems on a real project or an architectural interview.

At work or at a System Design interview, you often have to choose the best message broker. I plunged into this issue and will tell you what and why. What is better in each case, what are the advantages and disadvantages of these systems, and which one to choose, I will show with several examples.

How we listened to the needs of our customers and implemented the feature with the maximum capabilities of the iOS and Android platforms. Then we looked into analytics, added onboarding, and usage grew. At the end of the article there are some cool conclusions and insights. Developing a video conferencing mobile app is fun!

So far we've discussed query execution stages, statistics, and the two basic data access methods: Sequential scan and Index scan.

The next item on the list is join methods. This article will remind you what logical join types are out there, and then discuss one of three physical join methods, the Nested loop join. Additionally, we will check out the row memoization feature introduced in PostgreSQL 14.

Queries in PostgreSQL. Index scan

In previous articles we discussed query execution stages and statistics. Last time, I started on data access methods, namely Sequential scan. Today we will cover Index Scan.

Sometimes programming with mutexes gets too complicated and messy. Maybe you need to meet a new friend — the Event Loop pattern.

There is a list of well-known electronics design tools for Android which can be found in every review for the last 10 years: “Electrodoc”, “Every Circuit”, “Droid Tesla”, “Electronics Toolbox”, “RF & Microwave Toolbox” and so on. Also, there is a lot of trash on the market that turns finding a good tool into a quest.

This short review is about an unknown but cool tool “Circuit Calculator” working on Android devices and intended for professional electronics designers.

In Rust strings can be represented in two ways:

a)       String type

b)      String slice

String type:

String type is defined as a struct of the following structure:

Depending on arch (in my case x86 64bit it is 24byte)

{

   pointer to the address where string characters are stored (8b)

   capacity (8b)

   length (8b)

}

Once a upon a time I moved to brand new project. And without much thought, I decided to take DevOps responsibilities (after a long period of Frontend). Huge mono-repository (Angular and Node.js) gives rise to many specific problems. And this project was no exception. At the very beginning CI/CD duration was about 1.5h. And that was the biggest problem to take care of.

But at first, I want to talk about "Bourne again shell", cause CI/CD automation almost entirely was implemented by means of shell scripts (Bash). In context of huge mono-repo even regular build becomes a piece of odd stuff. That`s why a huge amount of scripts with complicated logic inside (build, test, deploy, generation of release notes, collection of logs and metrics, ...) was another significant problem.

Regardless of lang, quality of complex logic should be under control. It is no secret that key aspect of code quality control - is tests. For example, to refactor safely major logic should be covered with tests. We decided to keep shell scripts untouched and cover the major ones with tests before any refactoring. Of course, it is possible to use Jest (or Mocha) with a bunch of awful utils to test shell scripts. This approach is a bit wordy and has no value if scripts under test is written in Bash. Also I have no idea how to mock external shell commands (such as curl, ls, touch, npm, ...) with Jest or similar framework.

Hello! I'm kicking off another article series about the internals of PostgreSQL. This one will focus on query planning and execution mechanics.

In the first article we will split the query execution process into stages and discuss what exactly happens at each stage.

Flipper Zero is an open-source multi-tool for geeks and penetration testers. It so happened that the Flipper Zero project and the PVS-Studio analyzer crossed paths. A philosophical question: should we check the project, if the project developers have already started fixing errors? Let's try to do this.

Back in 2016 an United States based music composer and performer Sergio Elisondo released an one-man band music album A Winner Is You (know your meme), with multi-instrumental cover versions of tunes from numerous memorable classic NES games. A special feature of this release has been its version released in the NES cartridge format that would run on a classic unmodified console and play digitized audio of the full album, instead of the typical chiptune sound you would expect to come from this humble console. I was involved with the software development part of this project.

This year Sergio makes a return with a brand new music release. This time it is all original music album You Are Error, heavily influenced with the video game music aesthetics. It also comes with a special extra. This time we have raised the stakes, and a new NES cartridge release includes not only the digitized audio, but full motion videos for each song, done in the silhouette cutout style similar to the famous Bad Apple video. Yet again, this project is crowdfunded via Kickstarter. It already got the asked amount in a mere 7 hours, but there is still a little time to jump on the bandwagon and get yourself a copy. In the meantime I would like to share an insight on the technical side of both projects.

SEPIC-Ćuk split-rail converter can be used to make positive and negative supplies from a single input voltage for relatively well-matched loads like operational amplifiers.

Transient models are time consuming. Average models reduce modeling time drastically.

The PWM switch average models for current- and voltage-mode are described in details in Christophe Basso’s book “Switch-Mode Power Supplies, Second Edition: SPICE Simulations and Practical Designs”. Using of these models for SEPIC and Ćuk converters is also shown.

This text shows how to use the PWM switch average model to design a split-rail SEPIC-Ćuk converter.

In this video tutorial, we will control a pair of brushless motors from a Raspberry PI computer. We will use one of the computer's USB ports to connect a network of brushless motor controllers. We will power the computer, the controllers, and the brushless motors using a single battery, similar to a autonomous vehicle design.

The first motor is an outrunner type, a kind of what you would use for a vehicle propulsion. The bigger motor comes with a quadrature encoder which means it can be used as a powerful servo.

I made a cable to power my set up. On one end, the cable has a socket for plugging the battery. The cable splits into a two parallel parts to power the controllers, and the Raspberry PI. The bottom part of the cable further splits to power a pair of brushless motor controllers.
By the way, the controllers need 7 to 60 Volts DC. I put proper connectors at the ends of the cable, so that I could just plug it into the controllers.

Servosila brushless motor controllers come in rectangular or circular form factors. The controllers have USB and CANbus ports for connecting to control computers such as Raspberry PI.

Asymptotic notations are used to represent the complexity or running time of an algorithm. It is a technique of defining the upper and lower limits of the run-time performance of an algorithm.  We can analyze the runtime performance of an algorithm with the help of asymptotic notations. Asymptotic notations are also used to describe the approximate running time of an algorithm.

Types of Asymptotic Notations

Following are the different types of asymptotic notations:

Many of us spend time in specialized telegram groups. The power over communication here belongs to random people with their own shortcomings. Conflict and abuse occurs regularly. Is there another way to keep order so that scam spam doesn't flourish and no one has total control over group members?

In my case, these thoughts led to the development and testing of a system that can be connected to your Telegram today.

Introduction

It was 1989 when 2 editors of Inc. magazine, George Gendron and Bo Burlingham made the nervous drive to Palo Alto, California. Not long beforehand they’d decided on who to name as Inc.’s Entrepreneur of the Decade, and finally, they would get a chance to interview him.

As they entered the offices of NeXT, their interviewee approached them. In his trademark jeans and turtleneck sweater, Steve Jobs led them up the stairs to his office and the interview commenced.

Securing an interview with Steve Jobs was rare, even in 1989. And, wanting to make the most of their time, the editors got straight to the point with their very first question:

“Where do great products come from?”

After a slight pause, and a shuffle in his chair, Jobs replied:

“I think really great products come from melding two points of view; the technology point of view and the customer point of view. You need both. You can't just ask customers what they want and then try to give that to them. By the time you get it built, they'll want something new.”

Silence overshadowed the room. Three decades later, and this powerful answer Jobs gave is something that still isn’t often internalized in companies. 

Collecting user feedback is incredibly important. As you’ll see examples of later in this article, launching surveys, asking onboarding questions, and conducting customer interviews are all vital tools for improving your product. 

But the true lesson that Steve Jobs gave all this time ago was that user feedback isn’t as simple as asking what users want, or what they think about your product, and making those changes. You have to dive much deeper.